highschool/Grade 9/Science/SNC1DZ/Unit_4_Physics_Study_Sheet.md

Unit 4: Physics

Terms

Term	Definition
Static Electricity	an imbalance of electric charge on the surface of an object
Electron	a negatively charged particle in an atom
Proton	a positively charged particle in the atom’s nucleus
Electric charge	a form of charge, either positive or negative, that exerts an electric force
Neutral charge	an object that has equal numbers of protons and electrons
Negatively charged object	an object that has more electrons than protons
Positively charged object	an object that has fewer electrons than protons
Electric force	the force exerted by an object with an electric charge; can be a force of attraction or a force of repulsion
Induced charge separation	a shift in the position of electrons in a neutral object that occurs when a charged object is brought near it
Charging by friction	the transfer of electrons between two neutral objects (made from different materials) that occurs when they are rubbed together or come in contact (touch)
Electrostatic series	a list of materials arranged in order of their tendency to gain electrons
Charging by conduction	charging an object by contact with a charged object
Grounding	connecting an object to a large body, like Earth, that is capable of effectively removing an electric charge that the object might have
Conductor	a material that lets electrons move easily through it
Insulator	a material that does not easily allow the movement of electrons through it
Charging by induction	charging a neutral object by bringing another charged object close to, but not touching, the neutral object
Electric discharge	the rapid transfer of electric charge from one object to another
Lightning	a bolt of electricity from sky :D
Current electricity	the controlled flow of electrons through a conductor
Electric circuit	a continuous path in which electrons can flow
Switch	a device in an electric circuit that controls the flow of electrons by opening (or closing) the circuit
Load	the part of an electric circuit that converts electrical energy into other forms of energy
Electrical energy	the energy provided by the flow of electrons in an electric circuit
Electric cell	a device that converts chemical energy into electrical energy
Fuel cell	?
Direct current (DC)	a flow of electrons in one direction through an electric circuit
Alternating current (AC)	a flow of electrons that alternates in direction in an electric circuit
Electrical power	the rate at which electrical energy is produced or used
Kilowatt-Hour	the SI unit for measuring electrical energy usage; the use of one kilowatt of power for one hour
Efficiency	comparison of the energy output of a device with the energy supplied
Circuit	a way of drawing an electric circuit using standard symbols
Series circuit	a circuit in which the loads are connected end to end so that there is only one path for the electrons to flow
Parallel circuit	a circuit in which the loads are connected in branches so that there are two or more paths for electrons to flow
Potential difference (voltage)	the difference in electrical potential energy per unit charge measured at two different points; measured in volts
Voltmeter	a device used to measure potential difference (voltage)
Electrical resistance	the ability of a material to oppose the flow of electric current; measured in ohms
Ohmmeter	a device used to measure resistance
Resistor	a device that reduces the flow of electric current
Ohm’s law	the straight line relationship between voltage and current; R = V/I
Electrolyte	Anything that conducts electrons, usually a liquid solution

Static Charges

• Static Charges: An unequal number of individual electric charges on the surface of an object.

• Basically, the charges are nearly fixed on the surface of an object.

• Net Charge: The total electrical charge of an object, in other words, the difference between the protons and electrons.

• An object is:

Charge	Condition
Positively Charged	When number of electrons are less than the number of protons
Neutrally Charged	When the number of electrons are the same as the number of protons
Negatively Charged	When the number of electrons are more than the number of protons

• Charge is basically the difference between the amount of protons and electrons, the greater the difference, the greater the charge.
• A greater charge between objects is determined by the amount of difference between the protons and electrons in each of the objects. The one with more difference has a greater charge.

Triboelectric Series / Electrostatic Series

• Different materials have different abilities to hold onto electrons
• Triboelectric Series: A list of material that is arranged according to their ability to hold on to electrons.

Table Of Tribolecetric Series Of Common Materials

Law Of Electric Charges

• Electric Charges: A charged object has the ability to exert a force (ability to exert energy)
  • This charges can either be Attractive force (pulling together) or repulsive force (pushing apart).

1. Objects that have like charges REPEL each other.
2. Objects that have opposite charges ATTRACT each other.
3. A neutral object is sometimes attracted to a charged object.

Charging Statics

• There are 3 methods in charging a neutral object

1. Charging by Fricion
2. Charging by Contact
3. charging by induction

• There are 3 methods in discharging a charged object

1. Ground
2. Discharge
3. Time

Charging By Friction

• When 2 objects of different materials rub against one another, the electrons moves between the objects, one loses electrons and the other gains electrons.
• The object that gains electrons becomes negatively charged, and the other becomes positevely charged.

Charging By Contact

• When two objects of different electric charge touch each other, they will balance the charge, by transferring electrons from one object to the other.
• There are alot of different scenarios.

1. When a postive touches a neutral object.
   • electrons are transferred from the netural object to the postive object.
2. When a negative touches a neutral object.
   • electrons are transferred from the negative object to the neutral object.
3. When a negative touches a negative object.
   • The object with more negative charge (more electrons) will transfer some of its electrons to the weaker charged object.
4. When a positive touches a positive object.
   • The object with less positive charge (more electrons) will share some of its electrons to the object with more protons.
5. When a positive touches a negative object.
   • The negative charged (more electrons) object will transfer its electron to the positively charged (less electrons) object.

Summary

1. When an positively charged object touches a neutral object, the electrons in the neutral object will more to the positively charged object.
2. When an negatively charged object touches a netural object, the electrons in the negatively charged object will more to the the neutral object.
3. When 2 charged objects touch, the one with more electrons will move its electrons to the one with the lower charge.

Charging By Induction

• Charging a neutral object by bringing another charged object close by, but not touching the neutral object.
• There are 2 types of this, one is temporary and one is more permanent.
• Grounding: When a object is really big like the Earth, it will remove the charge on the object and return it to neutral. The reason is due to the Earth’s size, so it can lose and gain electrons without any effect.

1. Charging by Induction temporarily: Induced Charged Separation

• The electrons in the charged object get attracted by the positive charges in the netural object, thus pushing away the electrons in the neutral object, in essence, its charge seperation.
• The like charges will be repelled from the induction point, and the opposite charges will be attracted to the induction point.
• After the charged object is removed, the object will reutrn neutral. This is why this is a temporary way of charging an object.

2. Charging by Induction Permanently: Induced Charge Separation + Ground

• Basically, after being touched by a charged object, the neutral object will have a temporary charge, then the ground removes some of the electrons in the object, and afterwards, the object stays positive.
• If the object is removed before the ground, it goes back to neutral, the ground must be removed first in order to permantely charge the object.

Conductors and Insulators

• A conductor is a type of material that allows electrons to flow easily throught it.
• A insulator is a type of material the has high resistance agains the flow of electrons throught it.

Example	Type
Lightning Rod	Conductor
Copper	Conductor
Silver	Conductor
Rubber	Insulator
Plastic	Insulator

How Lightning Works

• In the cloud, it acts as a giant electrical generator.
• Water droplets rise up and freeze and fall back, they are now either postive or negatively charged.
• The negative charges go to the cloud and the postiive charges move to the top.
• When the charges reunite, lightning will strike.

Dangers / Applications of Electrostatics

• Dangers:
  • Any sparks are small inginitions in places such as gas stations or oil refineries can cause fires and expolsions.
• Applications
  • remove pollutants
  • coat / paint surfaces
  • fabric softener sheets

Static & Current Electricity

• Static electricity: an imblanace of electric charge on the surface of an object. Generally, it happens in insulators.
  • Example: Static in hair, charging by conduction…
• Current electricity: The controlled flow of electrons through a conductor. Generally, it happens in conductors.
  • Example: Cell phone, computer, washing machine…

Types of Currents

• There are 2 types of current electricity, Direct current and Alternating Currnet (ACDC).

1. Direct Current

• The electricity flow in which the electrons flow in one direction only.
• Example: any device that use battery such as cell phone, IPod, alarm clock, camera, etc.

2. Alternating Current

• The electricity flow in which the electrons repeatedly reverse flow direction.
• Example: Any device that use electric power outlet such as television, printer, XBOX, etc.

Electrical Components Of Circuits

• 
• ### Mandatory Componenets

1. Energy Source: Releases energy to provide power to other componenets that are connected
   • Example Electrochemical cell, battery, electrical outlet…
2. Load: Converts electrical energy into other form of energy.
   • Example: Light bulb, heater, fan, motor…
3. Conductor: Allows Electricity to flow through them easily
   • Example: Copper wire, gold wire, silver wire.

Optional Items

1. Switch: Turns the electric circuit on or off by cutting off the path.
2. Measuring Device: Measures the electrical property of the circuit.
3. Fuse: Safety device to prevent further damage to other electrical components.

Batteries

• Electrochemical Cell: A package of chemicals that converts chemical energy into electrical energy.
• Battery: More than 1 cell / two or more electric cells in combination.
• Types of cell: dry (paste, like a AA battery), wet (liquid, like a Car battery).

Electrical Cells

• Device that converts chemical energy into electrical energy
  • i.e. portable devices (cameras, cellphones, flashlights)
• Consists of:
  • 2 electrodes in a conducting solution (electrolyte)
  • Electrodes = conductors (1 easily postively charged and the other easily negatively charged)
• Electrons in the electrolyte are repelled by the negative electrode and attracted to the positive electrode

1. Wet Cell (Voltaic Cell)

• 

2. Dry Cell

• 
• Rechargeable cells are called Secondary cells, while non-rechargeable cells are called Primary cells.

3. Specialized Cells

• Fuel cell
  • Generates using external fuel, works like an engine without a moving part, requires continous source of fuel and oxygen.
  • Operate far longer than a conventional electric cell
  • Generates non-polluting exhaust.
  • I.e Hyrdogen fuel cell: produces electrical energy by converting hyrdogen and oxygen into water
  • Uses:
    • Primary and backup power for commerical industrial and residential buildings.
    • Power fuel-cell vehicles.
• Solar Cell
  • Converts light energy into electrical energy.
  • Based on semi-conductor silicon.
  • Very low efficiency (the best is around 40-50% efficiency)

Generating Electricity

• Non-renewable energy source: energy source that cannot be replaced as quickly as its is used.
• Renewable energy source: energy source that can be re-used or replaced quickly.

Types of Energy

Type	Example
Nuclear	Nuclear reaction
Gravitational	Ball rolling down a hill
Chemical	Chemical reaction
Kinetic	Any movement
Sound	Voice, music
Thermal	Heat from fire
Electricity	Lightning, electricity in your home
Light	Sunlight, Microwave

Pros and Cons

Method	Advantage	Disadvantage
Fossil Fuel	- very low cost to generate electricity	Create pollution during mining and burning fossil fuels.
Biomass	- very low cost to generate electricity - renewable compared to fossil fuel	- create pollution during burning biomass - can result in lower food production
Nuclear	- low cost to generate electricity - needs very little fuel	- very high cost to construct and maintain - create radioactive waste - at risk during natural diasters
Hydroelectric	- low cost to generate electricity if large scale - no air pollution	- huge disruption to large area of envirnoment during construction - very highcost to construct
Tidal	- low cost to generate electricity - no air pollution	- huge disruption to large area of envirnoment during construction - very highcost to construct - very few suitable location(s)
Wind	- low cost to generate electricity - Can be built anywhere that has wind available	- the wind does not always blow, which means the electricity generated is not reliable - potiential danger to birds
Solar	- Can be built anywhere that has sunlight available - no cost on fuel - easy to install in remove areas - no air pollution	- Very low efficiency, which means a large are is needd to get enough sunlight - generally only works during daytime
Geothermal	- low cost to generate electricity - no air pollution|- veryfewsuitable location(s) <br>- veryhigh cost` to construct

Measurement in Electric Circuits

Electrical Quantity	Electrical Quantity Symbol	Unit of Measurement	Unit of Measurement Symbol	Instrument Of Measurement	Symbol For Insturment
Resistance	R	Ohms	Ω	Ohmmeter
Current	I	Amperes	A	Ammeter
Voltage	V	Volt	V	Voltmeter
Electric Charge	Q	Coulomb	C

1. Electric Charge

• Symbol for Electric Charge: Q.
• Unit for Electric Charge: Coulomb [C].
• 1C = the charge of \(`6.25 \times 10^{18}`\) electrons (6 250 000 000 000 000 000).

2. Electric Current

• The rate (speed) of the movement of electric charge (electrons) in an electric circuit.
• Symbol for Electrical Current: I.
• Unit for Electrical Current: Ampere [A].
• 1 A = 1 C per 1 s = 1 coulomb of charge moved pass a point in 1 second
• In an electric circuit, there are 2 convention of how electrons flow in the circuit.
  1. Conventional
     • electrons flows from the positive terminal to negative terminal.
  2. Electron flow
     • electrons flows from the negative terminal to positive terminal.
     • Correct way vuit it is not widely used.
• The electric currnet is measured by an ammeter.
  • It is connected in series to the item you wnat to measure, which means you put the ammeter infront or behind the item you want to measure.

3. Potential Difference / Voltage

• the difference in electrical potential energy when a charge moved between 2 points in an electric circuit.
• Symbol for Voltage: V.
• Unit for Voltage: Volt[V]
• 1V = 1J of energy per 1C of charge (each coulomb of charge have 1J have energy).
• The voltage is measured by a voltmeter.
  • It is connected in parallel to the item you want to measure, which means you create a new path for the voltmeter next to the item you want to measure.

4. Electrical Resistance

• The opposition to the flow of electric current in a material. This is a property of the material.
• Symbol for Electric Resistance: R
• Unit for Resistance: Ohms[Ω]
• The resistance is measure by an ohmmeter.
  • It is connected in parallel to the item you want to measure, which means you create a new path for the ohmmeter next to the item you want to measure.

• Reasons for resistance:

  • A load convert electrical energy into other energy
    • Example: light bulb convert electrical energy to light energy.
  • Setup the flow of circuit
    • Example: Resistor adjusts flow of circuit (like narrowing down a road)
  • Everything has resistance. Conductor has low resistnace. Insulator has high resistance.
    • Example: wire has an resistnace so low that it is ignored in many calculations.

Factors Affecting The Resistance of Wires

• 1. Type of Material

  • Copper has much less resistance than iron.
  • Analogy: Water flowing through a pipeful of gravel. Resistance depends on type of gravel.

• 2. Length of Wire

  • Longer wires have more resistance.
  • Analogy: Water flowing through a pipeful of gravel. Resistance depends on length of pipe.

• 3. Thickness

  • Narrower wires have more resistance.
  • Analogy: Water flowing through a pipeful of gravel. Resistance depends on diameter of pipe.

• 4. Temperature

  • Higher temperature gives more resistance (More particles moving around and blocking it).
  • A hot filament has more resistance tahn a cold filament because atoms in the hot filament vibrate more and the vibration increases the resistance.

Product Efficiencies

• Simply take the output / input x 100 and you get the percentage of the efficiency of your product.

Ohm’s Law

• Ohm’s law states that \(`V = IR`\), which means the volatage is equal to the current multiplied by the resistance.
• When given a circuit, with one unknown value such as I, simply use Ohm’s law to find the missing value.

Series Circuits

• In a series circuit, there are a set of rules where the current, voltage, and resistance follow.
• \(`I_T = I_1 = I_2 = I_3 \cdots = I_N`\)
• \(`V_T = V_1 + V_2 + V_3 \cdots + V_N`\)
• \(`R_T = R_1 + R_2 + R_3 \cdots + R_N`\)
• As MORE loads are added:
  • \(`R_T`\) increases because more loads are added.
  • \(`I_T`\) decreases because \(`R_T`\) increases.
  • \(`I_{load}`\) decreases because voltage and resistance are the same for each load.
  • \(`V_{load}`\) decreases because each load gets less voltage (\(`V`\)) (\(`V_T`\) supplied by battery gets divided by more loads).
  • Each light bulb has the less brightness (because brightness depends on voltage) (Less energy gets converted into heat and light in each light bulb).

Parallel Circuits

• In a parallel circuit, there are also a set of rules where the current, voltage, and resistance follow. The current and voltage rules are swapped in this case.
• \(`I_T = I_1 + I_2 + I_3 \cdots + I_N`\)
• \(`V_T = V_1 = V_2 = V_3 \cdots = V_N`\)
• \(`R_T = (R_1^{-1} + R_2^{-1} + R_3^{-1} \cdots + R_N^{-1})^{-1}`\) (I think).
• \(`R_T = (R_1 \times R_2)/(R_1 + R_2)`\) (Don’t really trust this more, this one is from Alexander Wang, haven’t been confirmed with the teacher).
• As MORE loads are added:
  • \(`R_T`\) decreases because more loads are added.
  • \(`I_T`\) increases because \(`R_T`\) decreases.
  • \(`I_{load}`\) stays the same because voltage and resistance are the same for each load.
  • \(`V_{load}`\) stays the same because each load gets the same voltage as before.
  • Each light bulb has the same brightness (because brightness depends on voltage).

Comparing Series And Parallel Circuits

Series Circuits	Parallel Circuits
- An electric circuit in which the compoenents are arranged one after another. - It has only one path along which electrons can flow. - If that path is interrupted, the whole circuit stops.	- An electric circuit in which the parts are arranged so that electrons can flow along more than one path. - An interruption in one path does not affect the other path in the circuit
Voltage (V): - Total voltage is determined by the battery used - Each load uses portion of the total voltage supplied by the battery - As the number of loads increases, the potiental difference (voltage) for each load decreases	Voltage (V): - Total voltage is determined by the battery used - Voltage across parallel resistors will always be the same, even if the resistors have different values - As the number of loads increases, the potiental difference (voltage) for each load stays the same
Current (I): - The current is the same throughout a series circuit - As the number of loads increases, the total current decreases	Current (I): - Each load uses portion of the total current from the battery - As the number of loads increases, the total current increases
Resistance (R): - Total resistance increases when more resistors / loads are added - As the number of loads increases, the total resistance increases	Resistance (R): - Total resistance decreases when more resistors / loads are added - As the number of loads increases, the total resistance decreases